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For the treatment of patients 1 to 21 years old with relapsed or refractory acute lymphoblastic leukemia after at least two prior regimens. This indication is based upon response rate

16.01.2018

Clofarabine is a purinenucleosideantimetabolite marketed in the US and Canada as Clolar. In Europe and Australia/New Zealand the product is marketed under the name Evoltra. It is FDA-approved for treating relapsed or refractory acute lymphoblastic leukaemia(ALL) in children after at least two other types of treatment have failed. It is not known if it extends life expectancy. Some investigations of effectiveness in cases of acute myeloid leukaemia (AML) and juvenile myelomonocytic leukaemia (JMML) have been carried out. Ongoing trials are assessing its efficacy, if any, for managing other cancers.

Clofarabine is a purine nucleoside antimetabolite that is being studied in the treatment of cancer. It is marketed in the U.S. and Canada as Clolar. In Europe and Australia/New Zealand the product is marketed under the name Evoltra.

Clofarabine is used in paediatrics to treat a type of leukaemia called relapsed or refractory acute lymphoblastic leukaemia (ALL), only after at least two other types of treatment have failed. It is not known if the drug extends life expectancy. Some investigations of effectiveness in cases of acute myeloid leukaemia (AML) and juvenile myelomonocytic leukaemia (JMML) have been carried out.

For the treatment of pediatric patients 1 to 21 years old with relapsed or refractory acute lymphocytic (lymphoblastic) leukemia after at least two prior regimens. It is designated as an orphan drug by the FDA for this use.

Approval

Side effects

Tumor lysis syndrome (TLS). Clofarabine quickly kills leukaemia cells in the blood. The body may react to this. Signs include hyperkalemia, hyperuricemia, and hyperphosphatemia. TLS is very serious and can lead to death if it is not treated right away.

Other side effects. The most common side effects are stomach problems (including vomiting, diarrhea, and nausea), and effects on blood cells (including low red blood cells count, low white blood cell count, low platelet count, fever, and infection. Clofarabine can also cause tachycardia and can affect the liver and kidneys.

Contraindications

Drug interactions

Delivery

Dosage is a 2-hour infusion (52 mg/m²) every day for five days. The cycle is repeated every 2 to 6 weeks.

Regular blood tests to monitor his or her blood cells, kidney function, and liver function.

Biology

Clofarabine is a second-generation purine nucleoside analog designed to overcome biological limitations observed with ara-A and fludarabine. A 2´(S)-fluorine in clofarabine significantly increased the stability of the glycosidic bond in acidic solution and toward phosphorolytic cleavage as compared to fludarabine.[1] A chlorine substitution at the 2-position of the adenine base avoids production of a 2-fluoroadenine analog, a precursor to the toxic 2-fluoro-adenosine-5´-triphosphate and prevents deamination of the base as compared to ara-A.[2]

Clofarabine can be administered intravenously or given orally. Clofarabine enters cells via hENT1, hENT2, and hCNT2, where upon it is phosphorylated by deoxycytidine kinase to generate clofarabine-5´-monophosphate. The rate-limiting step in clofarabine metabolism is clofarabine-5´-diphosphosphate. Clofarabine-5´-triphosphate is the active-metabolite, and it inhibits ribonucleotide reductase, resulting in a decrease cellular dNTP concentrations, which promotes greater incorporation of clofarabine-5´-triphosphate during DNA synthesis. Embedded clofarabine-5´-monophosphate in the DNA promotes polymerase arrest at the replication fork, triggering DNA repair mechanisms that without repair lead to DNA strand breaks in vitro and cytochrome c-mediated apoptosis in vitro. Studies using cell lines have shown that clofarabine-5´-triphosphate can also be incorporated into RNA.[3]

Mechanisms of resistance and turnover have been reported. Clofarabine-resistance arises from decreased deoxycytidine kinase activity in vitro.[4] ABC transporter ABCG2 promotes export of clofarabine-5´-monophosphate and thus limits the cytotoxic effects of this analog in vivo.[5] Biochemically, clofarabine-5’-triphosphate was shown to be substrate for SAMHD1, thus potentially limiting the amount of active compound in cells.[6]

Synthesis

Production of Clofarabine
The reaction flask was added 2-chloro-9-(2-deoxy-2-fluoro-3,5-di-O-benzoyl-beta-D arabinose yl) adenine 1.5g (3mmol) and methanol 40ml,mixed with stirring. Then it was added sodium methoxide, 0.05g (content> 50%), the reaction was stirred for 40min. Then the mixture was cooled to room temperature, adjusted to pH 7 with acetic acid, filtered, and the filter cake was washed with an ice-methanol 10ml, added to the methanol 40ml, and heated to 63 °C, and then cooled to -10 o C. Still 1h, filtered, and the filter cake was washed with an ice-methanol 10ml, drained, dried under reduced pressure to give an off-white powdery solid clofarabine 0.48g. The yield is 54%.

Reaction of 1,2:5,6-di-O-isopropylidene-3-O-tosyl-a-D-allofuranose (I) with KF in acetamide at 210 oC gives 3-deoxy-3-fluoro-1,2:5,6-di-O-isopropylidene-a-D-glucofuranose (II), which is treated with a 1:1 mixture of metha-nol and 0.7% aqueous H2SO4 to yield 3-deoxy-3-fluoro-1,2-isopropylidene-a-D-glucofuranose (III). Selective acylation of the sugar (III) with benzoyl chloride in pyridine affords the 6-O-benzoyl derivative (IV), which is treated with Amberlite IR-100 (H+) ion-exchange resin in hot dioxane to provide 6-O-benzoyl-3-deoxy-3-fluoro-D-glucofuranose (V). The oxidative cleavage of glucofuranose (V) by means of KIO4 in water results in rearrangement to give 5-O-benzoyl-2-deoxy-2-fluoro-3-O-formyl-D- arabinofuranose (VI), which is deformylated by means of NaOMe in methanol to provide 5-O-benzoyl-2-deoxy-2-fluoro-D-arabinofuranose (VII). Acylation of the arabinofuranose (VII) with acetic anhydride in pyridine affords the 1,3-di-O-acetyl derivative (VIII), which is treated with HBr in AcOH/CH2Cl2 to yield 3-O-acetyl-5-O-benzoyl-2-deoxy-2-fluoro-D-arabinofuranosyl bromide (IX). Condensation of compound (IX) with 2-chloroadenine (X) by means of potassium tert-butoxide in different solvents gives the acylated 2-chloroadenosine derivative (XI), which is finally deacylated by means of NaOMe in methanol

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DR ANTHONY MELVIN CRASTO, Born in Mumbai in 1964 and graduated from Mumbai University, Completed his Ph.D from ICT, 1991,Matunga, Mumbai, India, in Organic Chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues, Currently he is working with GLENMARK PHARMACEUTICALS LTD, Research Centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India. Total Industry exp 30 plus yrs, Prior to joining Glenmark, he has worked with major multinationals like Hoechst Marion Roussel, now Sanofi, Searle India Ltd, now RPG lifesciences, etc. He has worked with notable scientists like Dr K Nagarajan, Dr Ralph Stapel, Prof S Seshadri, Dr T.V. Radhakrishnan and Dr B. K. Kulkarni, etc, He did custom synthesis for major multinationals in his career like BASF, Novartis, Sanofi, etc., He has worked in Discovery, Natural products, Bulk drugs, Generics, Intermediates, Fine chemicals, Neutraceuticals, GMP, Scaleups, etc, he is now helping millions, has 9 million plus hits on Google on all Organic chemistry websites. His friends call him Open superstar worlddrugtracker. His New Drug Approvals, Green Chemistry International, All about drugs, Eurekamoments, Organic spectroscopy international,
etc in organic chemistry are some most read blogs He has hands on experience in initiation and developing novel routes for drug molecules
and implementation them on commercial scale over a 30 year tenure till date Dec 2017, Around 35 plus products in his career. He has good knowledge of IPM, GMP, Regulatory aspects, he has several International patents published worldwide . He has good proficiency in Technology transfer, Spectroscopy, Stereochemistry, Synthesis, Polymorphism etc., He suffered a paralytic stroke/ Acute Transverse mylitis in Dec 2007 and is 90 %Paralysed, He is bound to a wheelchair, this seems to have injected feul in him to help chemists all around the world, he is more active than before and is pushing boundaries, He has 9 million plus hits on Google, 2.5 lakh plus connections on all networking sites, 50 Lakh plus views on dozen plus blogs, He makes himself available to all, contact him on +91 9323115463, email amcrasto@gmail.com, Twitter, @amcrasto , He lives and will die for his family, 90% paralysis cannot kill his soul., Notably he has 19 lakh plus views on New Drug Approvals Blog in 216 countries......https://newdrugapprovals.wordpress.com/ , He appreciates the help he gets from one and all, Friends, Family, Glenmark, Readers, Wellwishers, Doctors, Drug authorities, His Contacts, Physiotherapist, etc

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